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Gearheads, I need your help!

H. Vachon

H. Vachon

King of the Hobo Hut
Joined
Aug 30, 2019
Messages
4,143
Howdy friends. I’ve been having an issue for a while now where my truck will sound like it’s blowing off if it builds a bunch of pressure quickly. It’s a relatively short burst, but I don’t hear it in my buddy’s truck with the same engine (3.5 Ecoboost).

I’ve checked all vacuum lines as well as the hose fittings for both the hot and cold side of the intercooler.

No evidence of oil anywhere on the hoses or intercooler like you would normally see if you were leaking boost.

I can still hear the turbos wind up so I don’t think that’s the problem, but I’m thinking maybe a wastegate issue or something of the sort. Both blow off valves have been replaced since the noise started, and I’m still dead in the water. Any suggestions would be greatly appreciated. Thanks!!
 
What year, make, model (Obviously a Ford)?

When you say blowing off, do you mean like back out under the hood from the intake plenum area, or out the exhaust?
 
Oil overfilled? Bad fuel injector? There was a problem 05-06 in the 5.4s with cam phasers , not sure if the 3.5 has them.

Ignition coil?

Are you losing power?
 
I did some quick searching on some ecoboost forums I’m a member of (yes I have a 3.5 as well) and maybe it’s warped exhaust manifolds? Was just something that I ran into though. A video of the sound and when it’s happening (cold, idle, on throttle, warmed up, etc) would shed some more light on it.
 
2012 F150 3.5 Ecoboost

I don’t have a video.

Ironically I had the exhaust manifolds changed when I bought the truck. They dicked around and didn’t have it right the first time. The second time they left all the vacuum lines and shit disconnected. So I guess I’ll start there. Thanks!
 
So upon review a few videos. The manifold was my initial problem. That has been resolved. This isn’t a squealing like the manifold leak (mine was a broken stud) this actually sounds like a blow off valve.

John, it’s from under the hood, not the exhaust.
 
I worked for Roush on Ford prototype vehicles, I may be able to help or have contacts who can.
The blow off noise, does it happen when your rpms are high or just after you let off of the accelerator?
 
The noise of concern happens when the rpms are still climbing. It’s about twice the duration of a normal blow off when letting off the accelerator.

Part of me wondered if it was just a rush of air being pulled through the CIA. But the idle pitch of the CIA is deeper than this.
 
Mmmk, when work was performed on the truck was any sound deadening insulation removed?

Do you notice a lack of power during rapid acceleration?
 
Eqwhipped said:
Mmmk, when work was performed on the truck was any sound deadening insulation removed?

Do you notice a lack of power during rapid acceleration?
Click to expand...
No to the insulation.

There’s a bit of turbo lag, which doesn’t surprise me. The truck also weighs 7000#, is lifted and on 35s. It’s certainly not quick, but there is no noticeable loss of power
 
You might want to look at the BOV’s again, unless they are just recently replaced. It’s possible that one or both could have gone bad again or has a bad connection to it or something. Sorry for my rudimentary wording as I don’t have a lot of hands on knowledge with the system.

Other than that, you say it’s not a warped manifold, and I agree as the sound your describing doesn’t represent the “angry cricket” sound that you hear on most videos.

I did find one guy who said he had a similar sound and it ended up being the turbos, as replacing them fixed his issue. The take away I got from that was he also said he noticed that gaskets between the turbo and exhaust manifolds were both warped and cracked, and he suggested checking the 3 bolts holding the turbo to the manifold to see if they were loose, before investing in new turbos. That if loose, that gasket may be the cause.

Seems to me that if that gasket wasn’t sealed there, it could make a similar sound?
 
{tpc} said:
You might want to look at the BOV’s again, unless they are just recently replaced. It’s possible that one or both could have gone bad again or has a bad connection to it or something. Sorry for my rudimentary wording as I don’t have a lot of hands on knowledge with the system.

Other than that, you say it’s not a warped manifold, and I agree as the sound your describing doesn’t represent the “angry cricket” sound that you hear on most videos.

I did find one guy who said he had a similar sound and it ended up being the turbos, as replacing them fixed his issue. The take away I got from that was he also said he noticed that gaskets between the turbo and exhaust manifolds were both warped and cracked, and he suggested checking the 3 bolts holding the turbo to the manifold to see if they were loose, before investing in new turbos. That if loose, that gasket may be the cause.

Seems to me that if that gasket wasn’t sealed there, it could make a similar sound?
Click to expand...
BOVs we’re replaced/upgraded less than a year ago. I’ll dig into it this weekend and check the bolts. The passenger side is easy enough to get to, the drivers side is a bitch and a half 🤣

I’ll also check for signs of a leak coming off the turbo. Thank you sir
 
H. Vachon said:
BOVs we’re replaced/upgraded less than a year ago. I’ll dig into it this weekend and check the bolts. The passenger side is easy enough to get to, the drivers side is a bitch and a half 🤣

I’ll also check for signs of a leak coming off the turbo. Thank you sir
Click to expand...
I thought I read somewhere that it’s easier to get at the drivers side from underneath or through the wheel well, but that’s just my memory and it’s not always worth a shit lol.

It would be nice if it is just that gasket. You could check the manifold side with a straight edge maybe for warpage, if you think the gasket needs replacement and had everything apart. However if it was me I would probably just try the gasket anyway, to see if it helped.

The thought of it being a wastegate issue could still be a possibility, but if it was something like the wastegate being stuck closed too long, I think you would be able to see the boost being higher than normal, assuming there is a boost gauge to look it. Of course at that point you would probably be making more power (higher boost), so the fact that the power is remaining somewhat normal as you described tends to eliminate that. If it was stuck open, you would have low boost I believe.
 
Well said TPC, I was trying to figure out how if it's not vacuum leak related or turbo pressure related. But also not a difference in performance how the air, hissing, chirping sound could be made. I believe it could be part of the blow off or waste gate system.

Did you run a diagnostic tool scan that scans for soft codes?

(Soft codes don't throw idiot lights)
 
Ok just throwing this out there (so you can see how slow it is at work for me lol). Some have described having a similar issue when a tube that connects to the charge pipe next to the MAP sensor has come off, or a crack in the charge pipe itself. Admittedly, I have no idea what a charge pipe is.

Just to beat the horse dead, a lot have said that they have had this happen when there was a small tear in the diaphragm of the BOV. Basically creating a boost leak, big enough to make noise but small enough that boost was still good.

The other thing I thought, but have not been able to confirm by reading was that if the wastegate had stuck closed and made much more boost than called for (under acceleration), wouldn’t the BOV open to try to fix that? But maybe I’m not understanding the action of the BOV correctly. I thought that they open when you go from a hard acceleration to a hard deceleration (letting off after a wide open throttle) to release the pressure that the turbo is still making? So if the turbo is making more than called for, maybe the BOV opens to release that as well?

I will see my son in law this weekend and ask him. The dragster he runs is supercharged but I wouldn’t be surprised if he could shed some light on it. Unfortunately I can’t get ahold of one of his former teammates who is/was a ford engineer as he went to a top fuel team so we don’t see him much anymore . His only negative comment about 1st gen ecoboosts had something to do with a cylinder problem…but I can’t recall exactly what it was. Not this though.
 
{tpc} said:
Ok just throwing this out there (so you can see how slow it is at work for me lol). Some have described having a similar issue when a tube that connects to the charge pipe next to the MAP sensor has come off, or a crack in the charge pipe itself. Admittedly, I have no idea what a charge pipe is.

Just to beat the horse dead, a lot have said that they have had this happen when there was a small tear in the diaphragm of the BOV. Basically creating a boost leak, big enough to make noise but small enough that boost was still good.

The other thing I thought, but have not been able to confirm by reading was that if the wastegate had stuck closed and made much more boost than called for (under acceleration), wouldn’t the BOV open to try to fix that? But maybe I’m not understanding the action of the BOV correctly. I thought that they open when you go from a hard acceleration to a hard deceleration (letting off after a wide open throttle) to release the pressure that the turbo is still making? So if the turbo is making more than called for, maybe the BOV opens to release that as well?

I will see my son in law this weekend and ask him. The dragster he runs is supercharged but I wouldn’t be surprised if he could shed some light on it. Unfortunately I can’t get ahold of one of his former teammates who is/was a ford engineer as he went to a top fuel team so we don’t see him much anymore . His only negative comment about 1st gen ecoboosts had something to do with a cylinder problem…but I can’t recall exactly what it was. Not this though.
Click to expand...
So the blow off valves are rated for 30-32 pounds of boost. The stock turbos build maybe 16 pounds. In theory if the wastegate was stuck closed and the BOV was blowing off, I would feel some type of surging or power loss (maybe?)

@Eqwhipped to answer your question, I haven’t checked for codes, but I can hook my laptop up to it and check it this weekend. I’ve been meaning to get in there and adjust my tire pressure set points anyway.
 
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